Occupationally-related, noise-induced hearing loss is one of the most severe of all threats to the industrial worker. In many industries, noise abatement and hearing conservation programs rely heavily on workers' use of personal hearing protection devices (HPD's) in the presence of high ambient noise. HPD's can indeed be effective in curbing audition problems if selected and used properly. However, available HPD's are known to vary widely in their noise attenuation characteristics and in their acceptability to workers. The proposed two-year research program will address two issues which have direct bearing on the selection of HPD's for specific industrial noise problems. Industrial noises vary immensely in terms of their sound power spectra, as do the sound attenuation spectra of HPD's. Unfortunately, at present are few data to aid a safety engineer in selecting an HPD for a specific type of noise problem. During the first year of the proposed research, a variety of industrial noise sources will be sampled, spectrally-analyzed, and catalogued. Various types of HPD's (earplugs, ear canal caps, and earmuffs) will then be tested for their attenuation capabilities for each type of industrial noise, using ANSI hearing threshold measurement procedures. Workers may refuse to wear hearing protection for a variety of reasons, but often because they assume that HPD's hinder verbal communication. At present, there exist little data to support or dispel this assumption. The second year of the project will be devoted to determining the effects of various HPD's on workers speech communication in various intensities and spectra of industrial noise. Both investigations will be conducted in a semi-reverberant sound chamber in the Auditory Systems Laboratory at Virginia Tech. The project will result in a final document including the results of the industrial noise sampling and guidelines for HPD selection given specific noise problem situations and speech communication issues.